I believe bunnymoney is referring to IDR's as Incentive Distribution Rights which is $ going to the General Partner. I don't know what % the G.P. currently receives but it caps at 50% of Distributive Cash Flow or DCF. It is based on a longevity scale which increases the % with time. If I have it right. Although, it may have to do with share price increasing % of IDR, as bunny suggests. In either case, I'm sure they ain't going to reduce their piece of the pie!
Yes, "incentive distribution rights" based on increasing distributions per share by the GP to the partners. When certain goals are met, such as $1/share, the GP gets to keep the originally agreed upon %.
It would seem the distribution would be cut in half by the split and therefor the IDRs might be less. I have not yet been able to locate the partnership agreement with IDR info. I would guess somewhere in the fine print are exceptions that relate to splits and maybe other events.